Shrub encroachment into grasslands has been a topic of significant ecological interest. This study synthesizes global data to assess the impacts of shrub encroachment on ecosystem structure and function. Using univariate analyses, meta-analysis, and structural equation modeling, the researchers tested the hypotheses that shrub encroachment does not necessarily lead to declines in ecosystem functions and that shrub traits influence the functional outcomes of encroachment. The analysis of 43 ecosystem attributes from 244 case studies worldwide revealed that some attributes consistently increased with encroachment (e.g., soil C, N), while others declined (e.g., grass cover, pH). Traits of shrubs were associated with significant, though weak, structural and functional outcomes of encroachment. The study found that shrub encroachment had mixed effects on ecosystem structure and functioning at global scales, and that shrub traits influence the functional outcome of encroachment. Therefore, a simple designation of encroachment as a process leading to functionally, structurally, or contextually degraded ecosystems is not supported by a critical analysis of existing literature. The study highlights that the commonly established link between shrub encroachment and degradation is not universal. The study also examined the functional and structural effects of shrub encroachment, finding that shrub encroachment is associated with general reductions in ecosystem functions and processes. However, trends in productivity under encroachment are not universally consistent. For example, in the western United States, Juniperus virginiana encroachment onto lower elevation grasslands and shrublands has been shown to increase net ecosystem productivity and alter the quantity and distribution of soil and plant C and N pools. However, conversion of native grasslands to Juniperus virginiana forests had relatively minor effects on potential soil N transformations and plant available N, at least half a century after forest establishment. The study also found that the effects of encroachment on biota are less clearly defined and highly variable. Increases in shrub cover in encroached woodland in eastern Australia have been reported to be associated with increases in some bird species but decreases in others. Richness of mammalian carnivores, reptiles and tortoises showed no significant trend in relation to increasing shrub cover at sites in the Kalahari, Arizona, and Texas. However, Benshahar et al. (1992) and Kerley and Whitford (2009) demonstrated increases in ungulates, kangaroo rats and birds respectively with encroachment. Similarly, ant richness has been shown to be variable; sometimes increasing and sometimes remaining the same in response to increasing woody encroachment. The study concludes that the term 'shrub encroachment' must be decoupled from the concept of degradation, given emerging evidence of the importance of shrubs in ecosystem processes and the fact that existing evaluations are heavily biased towards pastoral production systems. The study also highlightsShrub encroachment into grasslands has been a topic of significant ecological interest. This study synthesizes global data to assess the impacts of shrub encroachment on ecosystem structure and function. Using univariate analyses, meta-analysis, and structural equation modeling, the researchers tested the hypotheses that shrub encroachment does not necessarily lead to declines in ecosystem functions and that shrub traits influence the functional outcomes of encroachment. The analysis of 43 ecosystem attributes from 244 case studies worldwide revealed that some attributes consistently increased with encroachment (e.g., soil C, N), while others declined (e.g., grass cover, pH). Traits of shrubs were associated with significant, though weak, structural and functional outcomes of encroachment. The study found that shrub encroachment had mixed effects on ecosystem structure and functioning at global scales, and that shrub traits influence the functional outcome of encroachment. Therefore, a simple designation of encroachment as a process leading to functionally, structurally, or contextually degraded ecosystems is not supported by a critical analysis of existing literature. The study highlights that the commonly established link between shrub encroachment and degradation is not universal. The study also examined the functional and structural effects of shrub encroachment, finding that shrub encroachment is associated with general reductions in ecosystem functions and processes. However, trends in productivity under encroachment are not universally consistent. For example, in the western United States, Juniperus virginiana encroachment onto lower elevation grasslands and shrublands has been shown to increase net ecosystem productivity and alter the quantity and distribution of soil and plant C and N pools. However, conversion of native grasslands to Juniperus virginiana forests had relatively minor effects on potential soil N transformations and plant available N, at least half a century after forest establishment. The study also found that the effects of encroachment on biota are less clearly defined and highly variable. Increases in shrub cover in encroached woodland in eastern Australia have been reported to be associated with increases in some bird species but decreases in others. Richness of mammalian carnivores, reptiles and tortoises showed no significant trend in relation to increasing shrub cover at sites in the Kalahari, Arizona, and Texas. However, Benshahar et al. (1992) and Kerley and Whitford (2009) demonstrated increases in ungulates, kangaroo rats and birds respectively with encroachment. Similarly, ant richness has been shown to be variable; sometimes increasing and sometimes remaining the same in response to increasing woody encroachment. The study concludes that the term 'shrub encroachment' must be decoupled from the concept of degradation, given emerging evidence of the importance of shrubs in ecosystem processes and the fact that existing evaluations are heavily biased towards pastoral production systems. The study also highlights